Test: Singly Excited Magnetic System

Question 1

For a toroid to extract the energy from the supply system, the flux linkages of the magnetic field must be ________

Accepted Answer

changing or varying

Answer

zero

Answer

constant

Answer

any of the mentioned

Question 2

The energy stored in a magnetic field is given by ____________ where L = self-inductance and Rl=reluctance.

Accepted Answer

1/2 Li2

Answer

1/2 (mmf*Rl)²

Answer

1/2&empty;Rl

Answer

1/2 &phi;2i

Question 3

For a linear electromagnetic circuit, which of the following statement is true?

Accepted Answer

Field energy is equal to the Co-energy

Answer

Field energy is less than the Co-energy

Answer

Field energy is greater than the Co-energy

Answer

Co-energy is zero

Question 4

The electromagnetic force developed in any physical system acts in such a direction as to tend to _____________

Accepted Answer

increase the co-energy at constant mmf

Answer

decrease the co-energy at constant mmf

Answer

increase the co-energy at constant flux

Answer

decrease the co-energy at constant flux

Question 5

The electromagnetic torque developed in any physical system, and with magnetic saturation neglected, acts in such a direction as to tend to ____________

Accepted Answer

decrease the reluctance and increase the inductance

Answer

decrease both the reluctance and inductance

Answer

increase both the reluctance and inductance

Answer

increase the reluctance and decrease the inductance

Question 6

Magnetic stored energy density for iron is given by ______

Accepted Answer

1/2 B2/&mu;

Answer

1/2 B/&mu;

Answer

1/2 B2 &mu;

Answer

1/2 ∅² Rl

Question 7

When a current of 5A flows through a coil of linear magnetic circuit, it has flux linkages of 2.4 wb-turns. What is the energy stored in the magnetic field of this coil in Joules?

Accepted Answer

6

Answer

12

Answer

1.2

Answer

2.4

Question 8

The electromagnetic force and/or torque, developed in any physical system, acts in such a direction as to tend to ____________

Accepted Answer

decrease the magnetic stored energy at constant flux

Answer

decrease the magnetic stored energy at constant mmf

Answer

increase the magnetic stored energy at constant flux

Answer

increase the magnetic stored energy at constant current

Question 9

Consider a magnetic relay with linear magnetization curve in both of its open and closed position. What happens to the electrical energy input to the relay, when the armature moves slowly from open position to closed position?

Accepted Answer

W_elec = W_mech/2+W_fld/2

Answer

W_elec = W_fld

Answer

W_elec = W_mech

Answer

Welec = 0

Question 10

Electromagnetic force and/or torque developed in any physical system, acts in such a direction as to tend to ____________

Accepted Answer

increase both the field energy and co-energy at constant current

Answer

increase the field energy and decrease the co-energy at constant current

Answer

decrease both the field energy and co-energy at constant current

Answer

decrease the field energy and increase the co-energy at constant current

Singly Excited Magnetic System - Free MCQ Practice Test with solutions,

MCQ Practice Test & Solutions: Test: Singly Excited Magnetic System (10 Questions)